The present invention relates to a system for integration in or attachment to a twin hull water vessel such as a catamaran to modify the lean of the catamaran during a turn, and more specifically, to a catamaran turning system including a set of fixed hull-mounted inwardly-directed fins, a set of vertically movable plates mounted on the stern end of the hull, and a steering-dependent control system for automatically raising and lowering the plates during operation of the catamaran.
Monohull boats, including V hull and skiffs, inherently tilt inwardly, or towards the vertex of the arc, during a turn. Said another way, the deck surface is lower on the inside side of the turn, and the boat pivots on the centerline of the hull along the arc of the turn. This provides a feeling of stability insofar as the passenger is pressed into the deck (or seat) of the boat during a turn. Without this tilting motion the centrifugal force of the turn would make the passenger feel as if they were being “thrown” from the boat during a turn, similar to the sensation of being in vehicle without a seatbelt when it takes a sharp turn at a moderate or higher speed.
In a catamaran however, there is no single pivot point along the centerline of the boat because there are two hulls, each having separate centerlines. This creates equal pressure against the two hulls in a turn, and a deck that either remains horizontal or tilts away from the vertex of the turning arc during a turn. This causes some passengers to feel as if they are on the verge of being thrown overboard. This is depicted in FIGS. 2 and 3.
This disconcerting centrifugal force is a common complaint of catamaran passengers, and is considered in the industry to be a major deterrent to catamaran ownership. Accordingly, there is a need for a system that facilitates passenger comfort during catamaran turns. It is desirable that this system facilitates comfort by negating some of the effects of centrifugal force during a turn by introducing a “banking” motion. It is desirable that this system functions automatically during normal operation of the catamaran. It is desirable that this system can be integrated into existing catamaran designs during the manufacturing process, or retrofitted with relative ease to already manufactured vessels.